Remove a specific item from a list using LINQ

Question

I have a list containing some objects and want to use LINQ to remove a specific item but am not sure how to do that.

foreach (var someobject in objectList)
{
    if (someobject.Number == 1) // There will only one item where Number == 1.  
    {
        list.remove(someobject)
    } 
}

Answer 1

You cannot use a foreach to remove items during enumeration, you're getting an exception at runtime.

You could use List.RemoveAll:

list.RemoveAll(x => x.Number == 1);

or, if it's actually not a List<T> but any sequence, LINQ:

list = list.Where(x => x.Number != 1).ToList();

If you are sure that there is only one item with that number or you want to remove one item at the maximum you can either use the for loop approach suggested in the other answer or this:

var item = list.FirstOrDefault(x => x.Number == 1);
if(item ! = null) list.Remove(item);

The link to the other question i have posted suggests that you can modify a collection during enumeration in C# 4 and later. No, you can't. That applies only to the new concurrent collections.